Electrical alarm switch for safe doors and the like



Jan. 26, 1965 J. w. FLOTRON, JR 3,167,621

ELECTRICAL ALARM SWITCH FOR SAFE DOORS AND THE LIKE 2 Sheets-Sheet 1 Filed March 18, 1963 F G 5 lam 471072:

Jmwss M FLOTEIA'JE. Q 5% Jan. 26, 1965 J. w. FLOTRON, JR 3,167,621

ELECTRICAL ALARM SWITCH FOR SAFE DOORS AND THE LIKE 2 Sheets-Sheet 2 Filed March 18, 1963 #77; z wry,

United States Patent 3,167,621 ELECTRICAL ALARM SWITCH FOR SAFE DfltlRfi AND THE LIKE JQZHQS W. Flo'tron, lira, St. Louis County, M0,, assiguor to Potter Electric Signal Company, St. Louis, Mo., a corporation of Missouri Filed Mar. 18, 1963, Ser. No. 265,616 6 Claims. (Cl. 20tl6i.62)

This invention relates to electrical alarms for safe doors and the like. It is intended to meet the need for a standard alarm readily installed on safe and vault doors of varying types, and capable of transmitting that variety of signals which is needed for signal surveillance by a central station alarm oflice.

One type of alarm switch, intended for a generally similar type of signal transmission, is shown in the patent to Westphal, No. 2,943,308. This type is intended for installation on those safe doors which close flush with the level of the surrounding frame. It includes a housed alarm switch whose housing is mountable onto the safe door but overhangs it so as to close against the flush door frame. Switch operation is by means of a fixed pin installed in a hole which must be specially drilled through the door frame. The end of this fixed pin projects through an opening in the base of the overhanging switch housing, there to engage the switch mechanism.

Partly to protect the fixed pin from being sawed through, and partly to prevent swinging of his switch housing along the door surface (Westphal used merely a magnetic mount), he also provided the overhanging part of the switch housing with a heavy locating pin to project into a socket and drilled into the door frame, spaced from the fixed switch-operating pin.

Such an installation has certain shortcomings. The frames of safes and vault doors are of hard steel; they are not readily drilled by an ordinary steel drill, either all the way through to secure a fixed projecting pin, or even to a depth suflicient to provide a socket for the protective locating pin. Such drilling might impair the fire resistance of the safe or vault. Westphals apparatus is not suitable for those safe and vault doors which close inwardly of the surface of a frame, rather than fiush with it. The door frame surface may be so irregular or interrupted as to leave insuflicient smooth area for the necessarily large overhanging portion of switch housing. These complexities affect the insurability of the installation, as well as its ease, its certainty of operation, and preservation of the fire-resistant and burglar-resistant characteristics of the safe or vault.

I have discovered how to overcome all these obstacles, by a new method of switch installation which requires only a single shallow dimple in the door frame, and with simple switch apparatus which includes its own safeguard against tampering, and which is applicable to nearly all types of fit of door and frame, including non-lush framing.

The shallow dimple of the present invention demands no precise tolerance. It is sufiiciently shallow that it may be readily drilled into a hardened steel safe frame without prejudicing its fire resistance. It is drilled to a sufiicient diameter to receive a tubular protecting collar or guard which surrounds the spring-urged plunger of an alarmoperating switch. The outermost plunger end seats in the bottom of the dimple. The plunger itself is of adjustable length, and non-conductive. A pile of conductive leaf springs is used, including a principal leaf which urges the operating plunger outward, and other leaves spaced adjacent to it on both sides and provided with contacts which open and close progressively against the principal leaf and each other, to make and break circuits by which 3,167,621 Patented .Ian. 26, 1965 the entire necessary variety of signals is given. The collar guards the plunger from insertion of a blade between the switch housing and the frame; cutting into it would deflect the operating plunger and set off an alarm.

Non-flush frames present no obstacle to the present installation. The portion of the switch housing which contains the plunger is positioned against a portion of the frame suitable for dimpling and its spacing of the remainder of the housing from the safe door is taken up by an adjustable door mount. Since the portion of the switch housing which necessarily overhangs the door edge is small, the installation possesses nearly universal applicability.

In the accompanying drawings:

FIGURE 1 is a perspective view of a safe upon which has been mounted an electrical alarm embodying the present invention, connected to a junction box shown schematically.

FIGURE 2 is an enlarged fragmentary side view, partly in section, taken along line 22 of FIGURE 1.

FIGURE 3 is a front view of the device shown in FEG- URE 2, with the cover partly broken away to show the adjustable mounting provision.

FIGURE 4 is a sectional view taken along line 44 of FIGURE 3.

FIGURE 5 is a sectional view taken along line 55 of FIGURE 3.

FIGURE 6 is a somewhat enlarged fragmentary sectional view, partly schematic, taken along line 6-6 of FIGURE 3, showing the positions of the switch parts with the safe door open, the switch housing being shown in dashed lines.

FEGURE 7 is a schematic view and wiring diagram showing the junction box circuit connections, and the switch parts in their positions with the safe door closed as in FIGURE 2.

The utilization of the present device on a typical safe is shown pictorially in FIGURE 1, illustrating the housing of the switch pile fittedly mounted on the door of he safe, to overlap the fixed frame; the device being connected by a flexible cable to a junction box. As hereinafter described, the junction box receives a regulated flow of direct current over a wire (which may be a telephone wire) from a central station alarm ofiice, which monitors the current flow as it is affected by the switching mechanism shown.

The switch pile which operates the present alarm device may first be described. It is best shown in FIG- URE 6, in which its leaf pile is shown with their contacts in positions which they assume when the safe door is open and the cover of the pile is removed. Such a switch pile consists essentially of electrically conductive substantially fiat metal leaf springs, cantilever-mounted together at one end by spacers (usually insulators) so as to extend therefrom substantially parallel to each other. Near their other ends the leaf springs bear electrical contacts which open and close responsive primarily to the deflection of a principal leaf spring. In the present embodiment the deflecting end of such principal leaf spring is positioned by a plunger which extends downward, beyond the ends of the other leaf springs.

Reverting to FIGURE 6, the principal leaf spring 11 is third from the bottom of the pile. While conveniently it is electrically conductive over its entire length, in the embodiment shown only the short portion of it which connects points of contact 17 on its upper and lower surface is used in the circuit. The other leaf springs, hereafter referred to as secondary, are as follows: the current feed spring 12 located immediately beneath the principal leaf spring 11; the ground connector spring 13 located therebeneath, that is, lowermost in 3 the pile; the circuit connector spring 14 located immediately above the principal leaf spring 11; the short feed spring 15 to the cover tamper contact located thereabove; and the equally short cover tamper spring 16, which is uppermost in the pile. Except as between the two springs 14, 15 (which are electrically connected by a conductive spacer 21), contact points 17 are provided between each of the adjacent springs mentioned, to open and close as herein described.

The principal spring 11 has an operating end portion 18 projecting beyond the other springs at the deflecting end of the pile. The deflecting of its end portion 18 conrols the making and breaking of contact between the springs ii, 12, 13, 14; while the cover tamper spring 16 has an operating end portion 19' which controls the opening and the closing of the contacts between it and the feed spring 15.

At their fixed ends, the springs 11, i2, 13, 14, 15, 16 are mounted in registration in a pile and spaced from each other by rectangular spacers at their ends remote from their contacts. Save for the metal conductive spacer 21 between the springs 14, 15, the mounting spacers are all insulating spacers 22, formed typically of phenolic material. Above and below, additional insulating spacers 22 are provided to complete the pile of FIGURE 6. The springs 11-15 and the spacers 21, 22 have parallel aligned bores 23, 24 lined with tubular insulators such as the phenolic tubes 25, as, which surround mounting bolts 27, 25: whose heads are countersunk into the principal portion 32 of a base-level plate generally designated 31. Integral terminal ends 29 for electrical connections are provided on the current feed spring 12, the ground connector spring 13 and the cover tamper spring 16. Nuts 30 on the outer ends of the bolts 27, 23 are tightened to bear against the uppermost insulating spacer 22 and secure the pile in aligned assembly.

The base-level plate 31 serves as the base of the switch enclosure, and is the principal structural member of the assembly. Its shape is shown in FIGURE 3. Though integral and flat, it may be thought of as consisting of bot-h a principal portion 32., to be mounted onto the door of the safe or vault; and an overhanging end portion 33 to close flush against the frame surface adjacent to the door. One side of the plate 31 (the right side as shown in FIGURE 3) is cut inwardly near its upper and lower ends, and the portion between these cuts is flanged at 90 to provide the mounting flange 34, which extends nearly its entire length but not quite so. The flange 34 has holes 35 slotted perpendicularly to the base plate 31; in these, countersunk head mounting screws 36 equipped with lock nuts 37 are utilized (in case of non-flush safe doors, as noted below) to secure to the outer side of the flange 34, the 90 flange 39 of a supplementary mounting angle 38 employed beneath the principal plate portion 32 only, whose mounting face 46 may thereby be spaced beneath the base-level plate 31 by the screws 36. This adjustable spacing is set so as to coincide with the amount which the safe door frame a overhangs the door surface b when the door is closed, so that the overhanging plate portion 33 will then be positioned flush against the frame a. Mounting means is optional; short screws 49a may be used in the safe door b (as shown in FIGURE 2) or the mounting flange 4%? may be cemented onto the door surface b. Should the safe be of the type whose door closes flush with the frame surface, the mounting angle 38 is discarded and the undersurface of the principal plate portion 4b is itself mounted onto the door surface b.

Projecting perpendicular-1y outward from the base plate 31 are two cover attachment studs 41 by which a hous ing cover generally designated 42, having a top wall 42a and a continuous side wall 42b, extending to and abutting the base plate 31 is secured by cap nuts 41a. This provides a safe enclosure for the switch and the mounting screws 36, for (as shown in FIGURES 2-5) the mounting angle 38 is received within a narrow gap be- 4 tween the base plate flange 34 and the housing cover side wall 42b.

The overhanging plate end portion 33 has a circular aperture or opening, with a rimmed edge 43 terminating on its lower side (the side outward of the switch housing) in a tubular collar-like guard portion 44. This may be relatively shallow and still serve its function, hereinafter described. The shallow guard portion 44 shown was formed by extruding the metal of the plate end portion 33; it is best shown in FIGURE 6.

Through the operating end portion 18 of the principal spring 11 there extends and is mounted, by opposed locking nuts 45, a non-conductive (preferably nylon), adjustable plunger screw 47, having a plunger end 48 which extends through the rimmed opening 43, and is urged by the spring 11 to extend beyond the guard portion 44. Its adjusted position determines all the usual signalling functions or" the device, except the signal which occurs on removal of the housing cover 42. From the operating end 19 of the cover tamper spring 16 projects upwardly a non-conductive tamper block 51, which also may be nylon. The pressure of its outer end against the inner surface of the housing top wall 42a closes the contacts 19 between the cover tamper spring 16 and the feed spring 15. The size of the tamper block 50 may therefore be determined readily, and requires no careful adjustment.

The present device is installed in the following manner:

An area, against which the overhanging plate portion 33 may close, is selected along the frame a adjacent to a portion of the door b having sufficient flat area to accommodate the mounting flange of the mounting angle 38 (or, in case the door b closes flush with the frame a, to accommodate the principal base plate portion 32). A shallow recess or dimple 51 is drilled into the frame surface a of suflicient diameter and depth to readily accommodate the projecting collar or guard portion 44 of the rimmed opening 43 of the overhanging plate portion 33. Such recess 51 may be drilled relatively easily into even a hardened steel frame surface a because of the shallowness of the collar or guard portion 44. The dimple formed by the tip of a twist drill may be adequate; it will provide a recess bottom 52 whose depth is slightly greater at the center, thus permitting the plunger end 48 to bottom at a depth greater than that which receives the collar portion 44. Hence only a minimum of hardened steel need be drilled out to form the recess 51.

With the safe door b tightly closed and the screws 36 loosened, the mounting angle 38 is located on the safe door surface b so that the guard 44 will extend into the recess 51 and the plunger end 48 will bottom at the recess center. With its location established, the mounting flange 49 is mounted in such located position on the safe door (whether by screws 40a or by cementing or in other convenient manner). The screws 36 are then set to position the principal base plate portion 32 spacedly away from the door surface b so that the overhanging end portion 33 will close flush against the frame a, as the collar guard portion 44 is accommodated within the recess 51. When so closed flush, the collar guard 44 protects the plunger end 48 from tampering. Comparing FIGURES 2 and 4, it will be seen that regardless of the angle from which one approaches the plunger end 48, it is not accessible for tampering.

In flush door installations, the mounting procedure is even more simple, the principal base plate portion 32 being mounted onto the door surface in suitable position to accommodate the collar guard 44 similarly within the recess 51.

For proper switch operation, the length of projection of the plunger end 48 beyond the rimmed opening 43 is set as follows: When the plunger end 48 bottoms in the center of the recess 51, deflection of the principal spring 11 will deflect the leaf spring pile to make contact settings which establish the switch circuit for indicating a closed safe door, as would be normal at night. This switch circuit position is illustrated in FIGURE 7. In it, the contacts 17, 19 between adjacent leaf spring elements 12, 11, 14, 15 and 16 are closed; whereas the contacts 17 between the current feed spring 12 and the ground connector spring 13 are opened. Where used with a central station alarm system, the installation is completed by wiring the terminal ends 29 by three conductive connectors 54, 55, 56 to a remote station panel junction box generally designated 60.

As shown in FIGURE 7, the current feed spring 12 is connected by connectors 54 to the same post of the junction box 60 as a telephone or other direct current communication wire 59. A ground connector 55 connects the ground spring 13 to a grounding connection 58 of the panel 60. A circuit return connector 56 connects the cover tamper spring 16 at the panel 60 through a fixed resistor 57 to the grounding connection 58.

The manner of use of the device will now be apparent to those familiar with central station alarm installations. A single wire 59 of a telephone line supplies low voltage direct current at a regulated flow rate monitored at the central station, which employs familiar current limiting means and automatic surveillance alarm sounding and recording equipment, not shown. If such controlled and monitored flow of direct current is switched to ground through the resistor 57, as in the door-closed position, FIGURE 7, less current will flow than if routed directly to ground, as in the door-open position, FIGURE 6. In contrast to both, if the cover housing 42 is removed, the tamper 50 will spring outward to the FIGURE 6 position, breaking the door-closed FIGURE 7 circuit. The central office equipment will note therefrom that the circuit is open; no current is flowing.

For purpose of this specification, the rate of current flow when channeled through the resistor 57 to ground is referred to as normal; the rate of flow to ground when the resistor is by-passed is referred to as the ground flow rate; and the zero flow rate which results from an open circuit is referred to as open.

The transition from the FIGURE 7 closed door position to the FIGURE 6 open door position is as follows: When the safe door b starts to open, the bending of the principal spring 11 by the force of the plunger 47 is slightly lessened, first opening the contacts 17 between the principal spring 11 and the circuit connector spring 14 above it. This open circuit precedes the making of contact between the current feed spring 12 and the ground connector spring 13 beneath it. This progression of normalopenground is indicated on the central office monitoring equipment. If it occurs at the normal business hour for opening a safe, it is not an alarm signal; at other hours it will be recognized as an alarm signal. This progression is automatically distinguished by the central office equipment from a condition of accidental grounding of the circuit. It is also obviously differentiated from the continuing open circuit which results from removing the cover housing 42, or a disconnection of the device.

The plunger end 48 is protected by the collar or guard 43 from the insertion of a thin blade between the base plate overhanging portion 33 and the door frame a. Nevertheless, should anyone manage to pry at the plunger end 48, forcing it outward, this would so raise the principal spring 11 as to break its contact from the current fed spring 12 beneath it, thus signalling an open, which in the embodiment shown is to be recognized as an alarm.

A vibrator assembly might, if desired, be inserted in the pile as between the circuit connector spring 14 and the feed spring 15, to vibrate to open if the safe door or switch mechanism was struck. Other such modifications of the circuitry will suggest themselves to persons familiar with the art. Therefore, the present invention should not be construed narrowly, but rather as fully coextensive with the claims hereof.

I claim:

1. An alarm switch device for attachment to the outside surface of a door openable from and closable within a frame member which projects beyond the door, comprising a housing having a base plate including a plate end portion having an opening surrounded by a rim,

an electrical switch mounted in the housing and having an operating plunger projecting outwardly through the rimmed opening,

the plunger being spring-biased to extend beyond the rim of the opening,

the switch having a normal position at which the outward end of the plunger projects beyond said rim,

the switch further having an alarm position corresponding to a position of the operating plunger outwardly of the normal position,

the housing further having a mounting member adjustably spaceable beneath a portion of the base plate not including the end portion having the rimmed opening,

whereby the switch may be secured to the surface of the door in such spaced position that the undersurface of the base plate end portion will project beyond the door and close flush against such frame member.

2. An alarm switch device as defined in claim 1,

in combination with such a frame member and such a door openable from and closable within the frame member,

the frame member having an outer surface projecting beyond the outer surface of the door,

the frame member surface having a recess of such depth as to receive and abut the projecting end of the plunger when projecting to a length corresponding to switch position for indicating normally closed door.

3. An alarm switch device as defined in claim 1,

the rim of the opening having a tubular guard element projecting beyond the undersurface of the base plate end portion,

in combination with a frame member having a recess of such width and depth as to receive the tubular guard element and plunger end,

and having a recess bottom against which the plunger end abuts in switch position for indicating normally closed door position.

4. An alarm switch device for attachment to the outside surface of a door openable from and closable within a frame member having a recess in close proximity to the door, comprising a housing having a base plate mountable upon the door and including a plate end portion for extending over the frame member when so mounted and having a rimmed opening for registration with the recess of the frame member,

a collar surrounding the opening in said plate end portion and projecting outward from its rim a sufficient distance to extend into the recess when the door is so closed within the frame member,

an electrical switch mounted in the housing and having an operating plunger projecting outwardly through said opening,

the plunger being spring-biased to extend beyond the rim of the opening, and

having a normal position at which the outward end of the plunger projects beyond said rim, whereby to bottom in the recess when the door is closed,

the switch further having an alarm position corresponding to a position of the operating plunger outwardly of the normal position.

5. The alarm switch device as defined in claim 4,

wherein the electrical switch includes an electrically conductive principal leaf spring having a first end secured spacedly above the base portion, said first end having electrical connector means, said conductive leaf spring having a second end including a plunger mounting,

an electrically conductive secondary leaf spring in registration with and spaced from the principal leaf spring and having a first end secured spacedly above the base plate and insulated from said first end of the principal spring and including electrical connector means, and

contact means operable between the principal spring and the secondary spring, said contact means being located along the principal spring between its secured end and its plunger,

said plunger being nonconductive and mounted within the plunger mounting of said principal leaf spring, whereby said contact means operates in response to changes in the amount by which the said plunger end projects beyond said collar.

6. An alarm switch device for attachment to safe doors and the like, comprising a housing having a base plate mountable onto such safe door and having an end portion extending therebeyond,

said base plate end portion having an opening surrounded by a projecting collar,

an electrical switch mounted in the housing and having an operating plunger spring-urged to project outwardly through the collar,

the switch having a normal position at which the outward end of the plunger projects beyond said collar,

the switch further having alarm positions corresponding to positions of the operating plunger both outwardly and inwardly of the normal position,

in combination with a door frame member having an outer surface including a recess of sufiicient width and depth to accommodate said collar,

said recess being in registration with said opening in said base plate end portion when the plate is so mounted on the safe door,

the collar being received within the said recess when the door is closed, and

the plunger end thus abutting the bottom of said recess in its normal position.

References Cited by the Examiner UNITED STATES PATENTS 657,195 9/00 Guenther 200--61.73 1,853,456 4/32 Ross 292-346 2,246,676 6/41 Hainsworth 2006l.82 2,624,792 1/53 Fruh 340-276 2,943,308 6/60 Westphal 340276 3,047,699 7/62 Patti 200-6152 BERNARD A. GILHEANY, Primary Examiner.

ROBERT K. SCHAEFER, Examiner. 

1. AN ALARM SWITCH DEVICE FOR ATTACHMENT TO THE OUTSIDE SURFACE OF A DOOR OPENABLE FROM THE CLOSABLE WITHIN A FRAME MEMBER WHICH PROJECTS BEYOND THE DOOR, COMPRISING A HOUSING HAVING A BASE PLATE INCLUDING A PLATE END PORTION HAVING AN OPENING SURROUNDED BY A RIM, AN ELECTRICAL SWITCH MOUNTED IN THE HOUSING AND HAVING AN OPERATING PLUNGER PROJECTING OUTWARDLY THROUGH THE RIMMED OPENING, THE PLUNGER BEING SPRING-BIASED TO EXTEND BEYOND THE RIM OF THE OPENING, THE SWITCH HAVING A NORMAL POSITION AT WHICH THE OUTWARD END OF THE PLUNGER PROJECTS BEYOND SAID RIM, THE SWITCH FURTHER HAVING AN ALARM POSITION CORRESPONDING TO A POSITION OF THE OPERATING PLUNGER OUTWARDLY OF THE NORMAL POSITION, THE HOUSING FURTHER HAVING A MOUNTING MEMBER ADJUSTABLY SPACEABLE BENEATH A PORTION OF THE BASE PLATE NOT INCLUDING THE END PORTION HAVING THE RIMMED OPENING, WHEREBY THE SWITCH MAY BE SECURED TO THE SURFACE OF THE DOOR IN SUCH SPACED POSITION THAT THE UNDERSURFACE OF THE BASE PLATE END PORTION WILL PROJECT BEYOND THE DOOR AND CLOSE FLUSH AGAINST SUCH FRAME MEMBER. 